Benzoyl-salicylic acid and process of making same.



UNITED STATES PATENT OFFICE.

ERNST BLooH, OF BASEL, SWITZERLAND.

BENZOYL-SALICYLIC ACID AND PROCESS OF MAKING SAME.

Specification of Letters Patent.

Patented Sept. 19, 1905.

Application filed May 26, 1905. Serial No. 262,479.

To all whom it may concern:

Be it known that I, ERNST BLooH, pharmaceutical chemist, a citizen of the Swiss Republic, residing at Basel, Switzerland, have invented a certain new and useful Process of the Manufacture of Benzoyl-Salicylic Acid, of which the following is a specification.

According to Gerhardt (Ann. 6Z6? (J/wmz'e, Vol. 87 page 161) the action of benzoyl-chlorid on sodium salicylate yields a compound of the formula which is a flexible and viscous mass, difficult to purify, and capable of being split up easily into benzoic acid and salicylic acid by boiling with water. On the other hand, Limpricht (Ammlen der Chemc'e, Vol. 290, page 164:) has reported on a compound of the formula.

, oo.o.n. oH.c.H.

coon,

which he called benzoyl-salicylic acid, but which contains the benzoyl groupin the henzene nucleus and consequently a non-esterified hydroxyl group. An ester of benzoylsalicylic acid has been produced by Freer from dry sodium-salicylic ethyl-ether, (Journal filr Pralctc'sc/w O/temie, M F., Vol. 4:7, page 243.) On saponification this ester,

o.co.o.H. (CGH4. I C16H1r04) COOGzHt,

is, however, split up into benzoic acid and salicylic acid. Consequently it has not been found possible hitherto to produce free benzoyl-salicylic acid or its salts.

According to the present invention true benzoyl-salicylic acid,

CH o.oo.c.H.

4\OOOH,

tion of one molecule of salicylic acid to two molecules of sodium hydrate and the necessary quantity of water and evaporating to dryness, are formed into a thin paste by adding about twenty kilos of benzin, (petroleum spirit,) after which a mixture of 14.1 kilos of benzoyl-chlorid and twenty kilos of .benzin are poured over it in a receptacle provided with a reflux cooler and a stirrer, and the at first violent reaction is moderated by cooling, if necessary. Subsequently about sixteen kilos of benzin are added, and the agitator is kept in motion for about eight hours. The product of the reaction is separated from the benzin by filtration. Any remnant of unaltered benzoyl chlorid is removed by subsequent Washing with benzin. The product of the reaction is dried and then boiled with about twentyfive times its quantity of water, thereby causing benzoyl-salicylate of sodium, salicylate of sodium, and sodium-chlorid to enter into solution. The cooled and, if necessary, filtered solution, which has a slightly-acid reaction, is precipitated by means of acetic acid or a similarly-acting acid. On stirring the free benzoyl-salicylic acid separates out in a crystalline form. To relieve this acid from salicylic acid adhering to the same, it is recrystallized from dilute alcohol or precipitated from 5 its alcoholic solution by a suiiicient quantity of water.

Benzoyl-sali cylic acid is almost insoluble in cold water, sparingly soluble in hot water, easily soluble in ether, alcohol, and chloroform, and not soluble in petroleum spirit.

The acid crystallized from alcohol melts at 132 In aqueous solution containing alcohol it does not produce the chemical reaction characteristic of salicylic acid; but when boiled with alkalies it splits up rapidly into salicylic acid and benzoic acid, after which the presence of the former can be proved by means of chlorid of iron.

Benzoyl-salicylic acid is intended to be used for therapeutic purposes, either as such or in the shape of salts, esters, or other compounds.

What I claim is V 1. The process for the manufacture of benzoyl-salicylic acid, which consists in treating disodium salicylate with benzoyl-chlorid, after dilution with a suitable liquid, and separating the free acid from the sodium benzoylsalicylate resulting from the reaction, substantially as described. I I0 2. The process for the manufacture of benzoyl-salicylic acid, which consists in treating zoyl-salicylic acid, which is sparingly soluble in'water, easily soluble in ether, alcohol and chloroform, melting (after having been crystallized from alcohol) at 132 centigrade, capable of being split up into salicylic acid and benzoic acid by boiling with alkali, and obtainable by the process described.

In witness whereof I have set my hand hereunto in the presence of two subscribing witnesses.

ERNST BLOCH. WVitnesses:

GEO. GIFFORD, ALBERT GRAETER. 

